In case of a mobile product, an IC card uses a variety of protocols. The protocols include USB (Universal Serial Bus), IC-USB (Inter-Chip Universal Serial Bus), MMC (Multi-Media Card), ISO 7816 and so on.
The USB is a protocol implemented by INTEL, COMPAQ, IBM, DEC, Microsoft, NEC, and Northern Telecom to interface with PC peripherals. The IC-USB protocol is a new protocol established to facilitate communication between chips, and uses a conventional USB protocol. The MMC is a flash memory card, such as those used in a mobile digital device, and uses an MMC protocol. The ISO 7816 (International Organization for Standardization 7816) is a protocol of a contact-type IC card governed by the ISO.
Because IC cards generally support one protocol, they do not support a host using another protocol. This creates communication limitations with respect to the IC cards and the host.